11-19-2022 01:51 PM
Hi
Our branches are connected through WAN using 2 Links
One main from one service provider and secondry through another service provider and 3rd link 3G
1st and 2nd ISP links configured with BGP, all traffic go through 1st link as primary. Secondry link send traffic only when 1st link go down
The problem is that some sites LAN stop working as no DHCP inside the LAN when connecting the secondry link
When removing the 2nd link or shut down the interface, the LAN is working again
What could be the issue, I remember that I see the same issue earlier with another setup and found the problem at service provider site, they are advertising my subnets as /29 instead of /28 as I remeber
What could be the problem here ?
Thanks
11-19-2022 02:14 PM
The problem is that some sites LAN stop working as no DHCP inside the LAN when connecting the secondry link
I do not believe this is related to BGP config - but we are not sure how is your setup configured, how are you reaching DHCP?
is this BGP on the internet? what Router is this ? Would you happen to have any configuration and topology for us to understand the issue ?
11-19-2022 02:28 PM
if you config DHCP relay and the second link not provide the return back path from DHCP server to DHCP relay (router or SW) then the LAN client failed to get IP from DHCP.
connect second link and do ping from DHCP relay (Router or SW) to DHCP server.
11-20-2022 02:24 AM
Thanks for your replies
The DHCP server is internal to the site inside the site
But as you see the DHCP work again after disabling the secondry ISP link
11-20-2022 02:31 AM
The DHCP server is internal to the site inside the site
if this is inside the site on the same device? (I think you need to provide the config as requested before - so it's hard to say what is wrong and what is configured.)
11-20-2022 03:06 AM
DHCP server internal to site are it config with DHCP relay ??
11-20-2022 08:31 AM
Hello
Can you provide further information and if possible a topology of your branch sites please, You don’t mention if you are sung single or dual wan rtrs, what dynamic ibgp routing ( if any) is running on the lan, what device is servicing the inter-vlan routing and how the lan is connected to your wan rtrs
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